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\Huge \textbf{数值分析第一次理论作业} \\ [0.2cm]
\LARGE 林敬翊 3210300367 信息与计算科学

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\section{QA}
QA.cpp 运行结果为\\
The coefficients are: \\
a0: 2.17572\\
a1: 2.67041\\
a2: -0.238444\\

近似多项式为$y = 2.17572+2.67041x-0.238444x^2$.用matlab画出原数据点和所得的近似多项式如下：

\begin{figure}[H]
    \centering
    \includegraphics[scale=0.35]{QA..jpg}
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\section{Q2}
QB.cpp 运行结果为\\
Coefficients of the best-fit quadratic polynomial obtained by QR factorization:\\
  2.17572\\
  2.67041\\
-0.238444\\
Condition number of the matrix G in 2-norm:\\
19002\\
Condition number of the matrix R1 in 2-norm:\\
141.072\\
很明显可看出，矩阵 G 在二范数意义下的条件数确实要比 R1 在二范数意义下的条件数要大的多。
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